NAND flash semiconductor devices, as used in storage devices like e.g. the Grass Valley VENOM solid state recorders, are not error-free in operation. For writing, flash memory devices are physically accessed in a page-oriented mode, whereby one ‘page’ includes e.g. 1024 or 2048 data words and related error correction code. Future flash devices will have a 4096 bytes page size. Erase operations on a specific flash memory can be carried out on specific-size data ‘blocks’ only. Such data block may include 64 pages.
Some of the memory defects are already detected during production of the storage devices and the corresponding memory locations or pages are marked as ‘bad’ and not usable. Specific circuitry avoids information data being stored at such ‘bad’ locations. However, further memory defects will occur during the lifetime and operation of a flash semiconductor. A related processing must prevent that information data intended to be written in such newly defect sections of a flash memory will not be lost. A corresponding processing is described e.g. in WO2007/080031 A1 and in WO2006/108755A1.